The orange light on my iPhone screen seems to be on even when I’m not using my camera or microphone

If you see an orange dot it means that an app is currently using the phone’s microphone.

A green light dot at the top of your iPhone means an app is using your phone’s camera.

You should check in Privacy&Security which app is enabled to use the camera and the microphone

You can also in settings>general>background app refresh toggle these apps off in case they are completing their activity in the background

Also, check to make sure that you're not using a Wallpaper made from a screenshot that had that indicator showing.